Getting Started

This page will help you install and build your first React Native app. If you already have React Native installed, you can skip ahead to the Tutorial.

Quick Start

Building Projects with Native Code

Expo is the easiest way to start building a new React Native application. It allows you to start a project without installing or configuring any tools to build native code - no Xcode or Android Studio installation required (see Caveats).

Assuming that you have Node installed, you can use npm to install the Expo CLI command line utility:

npm install -g expo-cli

Then run the following commands to create a new React Native project called "AwesomeProject":

expo init AwesomeProject
cd AwesomeProject
npm start

This will start a development server for you.

Running your React Native application

Install the Expo client app on your iOS or Android phone and connect to the same wireless network as your computer. On Android, use the Expo app to scan the QR code from your terminal to open your project. On iOS, follow on-screen instructions to get a link.

Modifying your app

Now that you have successfully run the app, let's modify it. Open App.js in your text editor of choice and edit some lines. The application should reload automatically once you save your changes.

If you're curious to learn more about React Native, continue on to the Tutorial.

Running your app on a simulator or virtual device

Expo CLI makes it really easy to run your React Native app on a physical device without setting up a development environment. If you want to run your app on the iOS Simulator or an Android Virtual Device, please refer to the instructions for building projects with native code to learn how to install Xcode and set up your Android development environment.

Once you've set these up, you can launch your app on an Android Virtual Device by running npm run android, or on the iOS Simulator by running npm run ios (macOS only).

Caveats

Because you don't build any native code when using Expo to create a project, it's not possible to include custom native modules beyond the React Native APIs and components that are available in the Expo client app.

If you know that you'll eventually need to include your own native code, Expo is still a good way to get started. In that case you'll just need to "eject" eventually to create your own native builds. If you do eject, the "Building Projects with Native Code" instructions will be required to continue working on your project.

Expo CLI configures your project to use the most recent React Native version that is supported by the Expo client app. The Expo client app usually gains support for a given React Native version about a week after the React Native version is released as stable. You can check this document to find out what versions are supported.

If you're integrating React Native into an existing project, you'll want to skip Expo CLI and go directly to setting up the native build environment. Select "Building Projects with Native Code" above for instructions on configuring a native build environment for React Native.

Follow these instructions if you need to build native code in your project. For example, if you are integrating React Native into an existing application, or if you "ejected" from Expo or Create React Native App, you'll need this section.

The instructions are a bit different depending on your development operating system, and whether you want to start developing for iOS or Android. If you want to develop for both iOS and Android, that's fine - you just have to pick one to start with, since the setup is a bit different.

Xcode

The easiest way to install Xcode is via the Mac App Store. Installing Xcode will also install the iOS Simulator and all the necessary tools to build your iOS app.

If you have already installed Xcode on your system, make sure it is version 9.4 or newer.

Command Line Tools

You will also need to install the Xcode Command Line Tools. Open Xcode, then choose "Preferences..." from the Xcode menu. Go to the Locations panel and install the tools by selecting the most recent version in the Command Line Tools dropdown.

Java Development Kit

Android development environment

Setting up your development environment can be somewhat tedious if you're new to Android development. If you're already familiar with Android development, there are a few things you may need to configure. In either case, please make sure to carefully follow the next few steps.

If the checkboxes are grayed out, you will have a chance to install these components later on.

Once setup has finalized and you're presented with the Welcome screen, proceed to the next step.

2. Install the Android SDK

Android Studio installs the latest Android SDK by default. Building a React Native app with native code, however, requires the Android 8.1 (Oreo) SDK in particular. Additional Android SDKs can be installed through the SDK Manager in Android Studio.

The SDK Manager can be accessed from the "Welcome to Android Studio" screen. Click on "Configure", then select "SDK Manager".

The SDK Manager can also be found within the Android Studio "Preferences" dialog, under Appearance & Behavior → System Settings → Android SDK.

Select the "SDK Platforms" tab from within the SDK Manager, then check the box next to "Show Package Details" in the bottom right corner. Look for and expand the Android 8.1 (Oreo) entry, then make sure the following items are checked:

.bash_profile is specific to bash. If you're using another shell, you will need to edit the appropriate shell-specific config file.

Type source $HOME/.bash_profile to load the config into your current shell. Verify that ANDROID_HOME has been added to your path by running echo $PATH.

Please make sure you use the correct Android SDK path. You can find the actual location of the SDK in the Android Studio "Preferences" dialog, under Appearance & Behavior → System Settings → Android SDK.

Open the System pane under System and Security in the Windows Control Panel, then click on Change settings.... Open the Advanced tab and click on Environment Variables.... Click on New... to create a new ANDROID_HOME user variable that points to the path to your Android SDK:

The SDK is installed, by default, at the following location:

c:\Users\YOUR_USERNAME\AppData\Local\Android\Sdk

You can find the actual location of the SDK in the Android Studio "Preferences" dialog, under Appearance & Behavior → System Settings → Android SDK.

Open a new Command Prompt window to ensure the new environment variable is loaded before proceeding to the next step.

Watchman

Watchman is a tool by Facebook for watching changes in the filesystem. It is highly recommended you install it for better performance and increased compatibility in certain edge cases (translation: you may be able to get by without installing this, but your mileage may vary; installing this now may save you from a headache later).

Creating a new application

Use the React Native command line interface to generate a new React Native project called "AwesomeProject":

react-native init AwesomeProject

This is not necessary if you are integrating React Native into an existing application, if you "ejected" from Expo (or Create React Native App), or if you're adding iOS support to an existing React Native project (see Platform Specific Code).

Creating a new application

Use the React Native command line interface to generate a new React Native project called "AwesomeProject":

react-native init AwesomeProject

This is not necessary if you are integrating React Native into an existing application, if you "ejected" from Create React Native App, or if you're adding Android support to an existing React Native project (see Platform Specific Code).

Preparing the Android device

You will need an Android device to run your React Native Android app. This can be either a physical Android device, or more commonly, you can use an Android Virtual Device which allows you to emulate an Android device on your computer.

Either way, you will need to prepare the device to run Android apps for development.

Using a physical device

If you have a physical Android device, you can use it for development in place of an AVD by plugging it in to your computer using a USB cable and following the instructions here.

Using a virtual device

If you use Android Studio to open ./AwesomeProject/android, you can see the list of available Android Virtual Devices (AVDs) by opening the "AVD Manager" from within Android Studio. Look for an icon that looks like this:

If you have just installed Android Studio, you will likely need to create a new AVD. Select "Create Virtual Device...", then pick any Phone from the list and click "Next", then select the Oreo API Level 27 image.

We recommend configuring VM acceleration on your system to improve performance. Once you've followed those instructions, go back to the AVD Manager.

If you don't have HAXM installed, click on "Install HAXM" or follow these instructions to set it up, then go back to the AVD Manager.

If you don't have HAXM installed, follow these instructions to set it up, then go back to the AVD Manager.

Click "Next" then "Finish" to create your AVD. At this point you should be able to click on the green triangle button next to your AVD to launch it, then proceed to the next step.

Running your React Native application

Run react-native run-ios inside your React Native project folder:

cd AwesomeProject
react-native run-ios

You should see your new app running in the iOS Simulator shortly.

react-native run-ios is just one way to run your app. You can also run it directly from within Xcode or Nuclide.